Fixed all of the previously mentioned problems by myself and Jonas
Quinn.
Fixed up JOYP and hooked up JOYP interrupts, they work on JOYP writes as
well if your selection makes the low four bits change to != 0xF.
Added basic sprite emulation, very very very lousy but it works for
Tetris.
Fixed DAA, fuck that opcode. Fixes blargg's CPU tests 1 and 11 (for some
odd reason.) Only test 2 is failing, on the "EI" test. Maybe it relies
on STAT interrupts?
Did some other stuff.

Tetris is now 100% fully playable. But that renderer is an abomination.
Soooooo simplistic and missing so many edge cases.
But holy shit, a fully playable commercial game in three days. I would
have killed to have made that progress when I started on bsnes.